WASHINGTON -- A patch developed to treat attention deficit hyperactivity disorder in children received a negative review from a Food and Drug Administration scientist, who concluded the drug cannot be safely marketed.

The patch uses methylphenidate, the same drug that is in Ritalin. But FDA reviewer Dr. Robert Levin found the patch produces troubling side effects too often to be considered safe. His findings were in briefing documents released by the agency on Thursday in advance of a public meeting on the drug.

The reviewer's findings are not the final word. An independent panel of experts convened by the FDA is expected to consider on Friday whether the patch is effective and safe. The FDA has the final call on whether the patch can be made available, but the agency often follows the advice of its panels.

The patch, developed by Noven Pharmaceuticals of Miami and Shire Pharmaceuticals Group in the United Kingdom, goes on a child's hip for nine hours, according to submissions by the company. It releases into the body methylphenidate, a stimulant that calms children with ADHD. It is for children between the ages of 6 and 12.

Noven pitched the patch as a way to treat ADHD in children for whom taking pills is difficult or unpleasant. It can also be removed if it causes any side effects.

But some children who received the patch during trials reported decreased appetites, headaches, insomnia, nausea and developing tics, the FDA said. Some also had skin irritation where the patch was applied. These occurred more often than in children taking Concerta, a pill that uses methylphenidate, and those taking a placebo, the FDA said.

GAITHERSBURG, Md., Dec 2 (Reuters) - An experimental patch to treat children with attention deficit hyperactivity disorder (ADHD) is safe and effective but should carry certain restrictions, a U.S. advisory panel unanimously said on Friday.

The Food and Drug Administration is considering whether to approve the patch, made by Britain's Shire Pharmaceuticals Group Plc (SHP.L...) and U.S.-based Noven Pharmaceuticals Inc (NOVN.O...). The FDA usually follows the advice of its advisers.

The panel's decision came after a key FDA staff reviewer earlier on Friday said the patch should be approved, reversing his opinion, released on Thursday, that it was too risky.

"I have reconsidered this (earlier) recommendation for a number of reasons. I think some of the safety concerns remain, but they seem to occur to a lesser degree," Robert Levin, a staff reviewer in the FDA's Division of Psychiatry Products, told panelists.